Opinion of the Court
differently, stating three times that an accommodation is not required when it entails “substantial” “costs” or “expenditures.” Id., at 83, n. 14. This formulation suggests that an employer may be required to bear costs and make expenditures that are not “substantial.” Of course, there is a big difference between costs and expenditures that are not “substantial” and those that are “de minimis,” which is to say, so “very small or trifling” that that they are not even worth noticing. Black’s Law Dictionary 388 (5th ed. 1979).
The Court’s response to Justice Marshall’s estimate of the extra costs that TWA would have been required to foot is also telling. The majority did not argue that Justice Marshall’s math produced considerably “more than a de minimis cost” (as it certainly did). Instead, the Court responded that Justice Marshall’s calculation involved assumptions that were not “feasible under the circumstances” and would have produced a different conflict with “the seniority rights of other employees.” 432 U. S., at 83, n. 14; see Brief for United States 29, n. 4 (noting that Hardison “specifically rejected” the dissent’s calculations and that it is “wrong to assert” that Hardison held that a $150 cost was an undue hardship).
Ultimately, then, it is not clear that any of the possible accommodations would have actually solved Hardison’s problem without transgressing seniority rights. The Hardison Court was very clear that those rights were off-limits. Its guidance on “undue hardship” in situations not involving seniority rights is much less clear.
C
Even though Hardison’s reference to “de minimis” was undercut by conflicting language and was fleeting in comparison to its discussion of the “principal issue” of seniority rights, lower courts have latched on to “de minimis” as the governing standard.
To be sure, as the Solicitor General notes, some lower
